Kissing Spheres of Various Sizes (a plane of bubbles)
This kind of bubble effect can be generated using rigid bodies and force fields. A mix of different size spheres are dropped on a plane and the force field causes them to pull together and space fill.





Procedure (tested on Blender 2.79)


Create the baseline geometry. Add a contained to drop the spheres into, add sphere of different sizes above the container. Set the contained as a passive rigid body. Set the spheres as active rigid bodies.
Add a force field actuator to the center of the container, under the floor. Set the force to a negative value to attract the spheres.
Set the gravity to a high number to pull all of the spheres to the floor and keep them there as they are pulled to the center.
Animate until everything is pulled together.





At this point, the spheres are reasonably packed and approximate the 'kissing spheres' stuck to a plane. Add the shaders and render.




Example Blender file -